A passive optical network (PON) is one system for providing network access over “the last mile.” The PON is a point to multi-point network comprised of an optical line terminal (OLT) at the central office, an optical distribution network (ODN), and a plurality of optical network units (ONUs) at the customer premises. In current PON systems, the downstream data is broadcasted with no or infrequent interruptions from the OLT to the ONUs in the form of about continuous optical wave signals. On the other hand, the upstream data is transmitted from the ONUs to the OLT with more frequent interruptions or pauses in the form of optical burst signals. The optical burst signals' amplitudes can vary from one optical burst signal to another. As a result of the frequent pauses and the variations in the individual optical burst signals amplitudes, the average amplitude in the optical burst signals can fluctuate over time that results in DC voltage offset variation in the optical receiver. The varying DC offset can increase the time required by the optical receivers to adjust the decision threshold and distinguish between the individual “0” and “1” symbols, referred as level recovery. The excessive time required for level recovery in the optical receivers can reduce the optical receivers' detection capabilities as the optical burst signal rates increase, for example, from about 1.25 Gigabits per second (Gbps) to about 2.5 Gbps and about 10 Gbps.
An 8b10b code can be implemented to relax the optical receiver's time requirements, where eight-bit blocks of random data can be converted into ten-bit blocks of restricted code. However, the 8b10b code adds about a 25 percent bandwidth overhead. Alternatively, optical power equalization methods can be implemented using optical amplifiers (OAs), such as gain clamped Semiconductor OAs (SOAs), to smooth the optical burst signal to some degrees thus to reduce the DC offset variations in the optical receiver. The SOAs can also amplify the optical burst signals and compensate for transmission losses, which may result due to signal splitting in the ODN, signal attenuation over long travel distances, or both. However, optical power equalization using optical injection to the SOAs or using inversed input signal directly superposed on the bias current of SOAs becomes less efficient when the burst amplitude difference in the optical burst signals increase.